Superantigen activation of CD4+ and CD8+T cells from HIV-infected subjects: role of costimulatory molecules and antigen-presenting cells (APC)
T cell receptor (TCR) triggering via superantigens induces decreased proliferative responses and increased apoptosis in T cells from HIV-infected patients compared with controls. Our aim was to delineate the role of intrinsic T cell defects, of APC dysfunction and of cytokines and costimulatory signal dysregulation in the deficient responses of CD4+ and CD8+ T cells from HIV+ subjects to the superantigen Staphylococcus enterotoxin A (SEA). Proliferation and IL-2R alpha up-regulation on SEA-stimulated CD4+ and CD8+ T cells in whole blood were reduced in HIV+ subjects with CD4 counts < 500, compared with controls. Neither addition of IL-2, IL-12 or phorbol myristate acetate (PMA) nor neutralization of endogenous IL-10, tumour necrosis factor-alpha (TNF-alpha), TNF-beta or transforming growth factor-beta (TGF-beta) could restore the decreased activation by SEA. Possible intrinsic T cell defects were studied by presenting SEA on HLA-DR-transfected Chinese hamster ovary (CHO) cells, co-expressing LFA3 and/or CD80, to purified T cells. In this system CD8+ T cells from most HIV+ patients were hyporesponsive with regard to IL-2 production, IL-2R alpha up-regulation and proliferation, whereas clearly reduced responses were only shown in CD4+ T cells from AIDS patients. Similarly, apoptosis was increased in CD8+ T cells from all patients, but only in CD4+ T cells from AIDS patients. During HIV infection, the responses to TCR triggering through SEA are deficient in both T cell subsets. The intrinsic defect appears earlier during disease progression in purified CD8+ T than in CD4+ T cells, it occurs in conjunction with both CD2 and CD28 costimulation, and it is correlated with increased levels of apoptosis.
Vingerhoets
J
J
Institute of Tropical Medicine, Laboratory of Immunology, Antwerp, Antwerpen, Belgium.
Dohlsten
M
M
Penne
G
G
Colebunders
R
R
Sansom
D
D
Bosmans
E
E
Kestens
L
L
Vanham
G
G
D000818:Animals; D017951:Antigen Presentation; D000956:Antigens, Viral / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D016466:CHO Cells; D006224:Cricetinae; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D008213:Lymphocyte Activation; D018089:Superantigens / Q000276:immunology*
D000956:Antigens, Viral; D018089:Superantigens